1. Field of the Invention
The present invention relates to an input apparatus and an input method of a portable terminal using a pen. More particularly, the present invention relates to an apparatus and a method for compensating an input from a pen to increase the accuracy of the pen.
2. Description of the Related Art
A current portable terminal includes various input apparatuses. For example, the portable terminal generally includes a touch screen in which a touch sensor and a display unit are integrated. Also, the portable terminal having the touch screen is developed such that an input may be entered not only by a user's finger but also by a pen. Here, the pen may be an electric pen, such as an Electro Magnetic Resonance (EMR) pen. When using the pen input method, a user may generate various types of input such as a drawing and text data by using the pen. Therefore, the pen input apparatus is expected to be widely used in the future.
Generally, in use of an EMR pen, a coordinate of the pen may be detected through a signal applied to a basic sensor board and a controller extracts an input coordinate of the pen through an algorithm for basic interpolation and compensation.
However, in a method of extracting the input coordinate of the pen as described above, the coordinate extraction algorithm has a limitation in that an exact coordinate may not be extracted. Namely, when using the pen, a position of the extracted coordinate may be different according to a user's characteristic (e.g., whether the user is left handed or right handed, etc.). Also, the position of the coordinate may be different depending on an angle at which the pen touches the touch panel. Furthermore, the position of the coordinate may be different depending on a position of the touch panel relative to the user when the user uses the pen.
In addition, accuracy of the coordinate may be different depending on an area of the touch panel. In other words, a center area of the touch panel has higher accuracy while a peripheral area of the touch panel has lower accuracy due to the strength of a signal referenced for extracting the coordinate being weak in the peripheral area of the display panel as compared to the center area of the display panel. Accordingly, there is a need for an apparatus and a method for improving the accuracy of an input coordinate in a portable terminal equipped with an electric pen.